1. Field of the Invention
The present invention is directed to a process for the aldol condensation of carbonyl compounds, and for the substitution of a different carbonyl compound into the aldol condensation products.
2. Prior Art
The aldol condensation process is a well known commercial process for increasing the molecular weight of carbonyl compounds. It is used for the condensation of the same compounds or for the condensation of a mixture of compounds. The catalyst commonly used for aldol condensation is sodium hydroxide or other caustic material. Aldol condensations generally yield hydroxy carbonyl compounds. These compounds are usually dehydrated to the unsaturated carbonyl compound using an acid catalyst, e.g., acetone is condensed with a base to yield diacetone alcohol which is treated with an acid and dehydrated to mesityl oxide. The salt thereby produced is then filtered and then disposed. No catalyst suitable for commercial scale condensation of higher ketones (e.g. methyl isobutyl ketone) is known.
Schonberg and Jugens, Berichte 95, 2137-40 (1962); Tanaube et al., Chemical and Pharmaceutical Bulletin, II pp. 536; and Miller's U.S. Pat. No. 2,800,510 may have suggested preparing hydroxy carbonyl compounds without subsequent dehydration using an aluminum oxide catalyst. Prior art has also suggested reasonably efficient methods of condensing higher aldehydes with ketones (U.S. Pat. No. 2,000,017 and British Pat. No. 440,539).
Palmer and Cowan (British Pat. No. 921,510) suggest using an alkali-treated, activated-alumina catalyst (which could also be calcium chloride treated) to convert acetone to a mixture of mesityl oxide and diacetone alcohol. The catalytic effect in this case was due to the alkali, as zero conversion to mesityl oxide was reported when alkali treatment was omitted. Kojima (Nippon Kogake Koushi, 1974(7) Pgs. 1353-1355 suggests use of aluminum oxide treated with hydrochloric acid to obtain low yields of aldol condensation products.
Other patents of interest are:
______________________________________ U.S. Pat. No. British ______________________________________ 1,437,139 2,442,280 3,155,730 783,458 1,151,113 2,468,710 3,361,828 922,826 1,885,221 2,684,385 3,422,072 2,130,592 2,719,863 3,432,557 2,275,586 2,829,168 3,542,878 2,376,070 3,002,999 3,544,635 3,077,500 ______________________________________
As will be apparent from the above cited art, benefits of aldol preparation by carbon dioxide addition to aluminum compounds have not been previously recognized.